Programming languages

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Programming languages

• Kimberly C. Walls
• 2001

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Programming languages, or, talking to your
computer

• When do you talk to your computer?

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Whenever you want it do something!
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Talking to your computer

• Thank goodness you dont have to know the
  computers native language!

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Remember

• A computer CPU only understands digital
  information
• Each kind of CPU understands its own machine
  language

• Humans prefer to talk to computers through
  translation of source code into machine language

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Three types of translation

• Assembly
• Translates symbols and numbers
• Compilation
• Translates an entire source code source into
  machine language
• Interpretation
• Tranlates a line of code at a time

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Types of High-level Programming Languages

• Procedural
• Written sequentially (like a score with repeats,
  codas, etc., but with conditions)
• FORTRAN, COBOL (compilers)
• BASIC (interpreter)
• Structured procedural language
• Pascal, C

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Types of High-level Programming Languages

• Nonprocedural
• LISP List processor
• LOGO
• HyperLogo
• SQL database language
• Object-oriented programming (C, Visual BAISC,
  Max, Java

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Internet programming

• HTML HyperText Markup Language
• Uses tags to control layout
• Browser interprets tags
• XML Extensible Markup Language
• DHTML Dynamic HTML
• VisualBasic
• Java is machine-independent

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Internet programming

• Java applets are compiled to be downloaded with
  web pages
• Scripting languages
• VBScript (for Internet Explorer only)
• JavaScript
• ActiveX is API for VBScript and Explorer
• JavaBeans is API for JavaScript on any computer
  with Java

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Object-Oriented Programming OOP

• Objects are intelligent or have personality
  based on its handlers and properties
• Objects send messages to each other
• Handlers handle the messages
• External events send messages

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More OOP--The elements

• Objects--send and receive messages
• Messages--communications
• Methods--the handlers and properties
• Classes--groups with similar personalities
• Inheritance--new objects inherit from ancestors
  (handler may be in ancestors)

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OOP Scripting Languages

• HyperStudio HyperLogo
• HyperCard HyperTalk
• ToolBook OpenScript
• Director

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HyperStudio Objects

• Buttons
• Fields
• Hotwords
• Groups
• Cards
• Menus
• Stacks
• Painted images

• Drawn images
• Sounds
• Video
• MIDI
• CD

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HyperStudio Properties

• Name
• ID number
• Script
• Location
• Rectangle
• Visible (hidden or not)
• Font
• Font size

• Scroll property
• Highlight
• Icon
• Transparency
• Line size

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HyperStudio Messages

• Mouse Click
• Roll Over
• Open/Close Stack
• Open/Close Card
• Key Press
• Menu items

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HyperStudio Layers or Hierarchy

• Objects on top layer of card
• Objects underneath
• Card
• Stack
• HyperStudio
• OS

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HyperStudio Classes

• Buttons
• Fields
• Images
• Backgrounds
• Cards
• Pages
• Grouped items

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OOP in JavaScript

• Window object web page
• Elements of page are objects too

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Some JavaScript Object Properties

• window.length
• window.name
• window.document.bgcolor
• window.document.links
• window.location.pathname

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Some JavaScript Methods

• window.close()
• window.open()
• window.alert()
• window.prompt()
• window.document.writeln()
• window.scroll()

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Some JavaScript Event Handlers

• onload()
• onclick()
• onmouseover()
• onselect()
• onerror()

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Types of Programming Structures

• Actions--what to do
• Branch--make a choice
• Loop--repeat